The current Carbon Dioxide Removal Assembly (CDRA) onboard the International Space Station (ISS) is used to capture and compress CO2 from the cabin air and then deliver compressed CO2 to the Sabatier Reactor to make water and methane. The CDRA captures CO2 using a sorbent material, traditionally zeolite. The zeolite must be maintained at specific temperatures for successful adsorption (20°C) and desorption (200°C) of the CO2. The CDRA relies on cartridge heaters and solid conductive metal fins to generate and spread heat to the sorbent material. The cooling system connects to the main cooling system on the spacecraft. This thermal management system is employed to maintain the appropriate sorbent (i.e., zeolite) temperature for adsorption and desorption temperatures of the CO2. The current system has been used for over 30 years, and many problems have arisen during its lifetime including performance vs. resource usage, closed loop operation, zeolite dust causing leaks, and sensors failing due to thermal fatigue. The proposed thermal management system mitigates many of these issues by combining the heating and cooling modes, operating passively, and replacing the solid metal fins with a unique, two-phase heat transfer vapor chamber system. By using vapor chambers instead of solid metal fins, there is minimal temperature gradient along the heat transfer device which will increase the isothermality of the surrounding sorbent material. This allows for faster, and more even, heating and cooling of the sorbent bed, which will ultimately improve the CO2 adsorption and desorption rates.
This novel vapor chamber thermal management system would be used for the current Carbon Dioxide Removal Assembly (CDRA) on board the International Space Station. It will allow for less power usage, combined heating and cooling mode, high isothermality in the sorbent material, and a more efficient carbon dioxide removal assembly. This concept can also be applied to future metal organic framework assemblies or liquid sorbent systems for carbon dioxide removal.
This novel vapor chamber design can be applied to other CO2 capture systems that utilize a temperature sensitive zeolite. This includes direct air capture systems, systems capturing CO2 from truck exhaust, or systems filtering exhaust from manufacturing facilities. Theoretically, the vapor chamber can be retrofitted to suit the needs of any sized zeolite bed.